Brainstem and cranial nerves Flashcards
What makes up brainstem?
1) Midbrain
2) Pons
3) Medulla oblongata
What are 2 divisions of midbrain?
Dorsal tectum
Ventral tectum
Locate the pons?
Brainstem
Between midbrain and medulla
What structure in brainstem is continuous with spinal cord?
Medulla oblongata
Where is interpenduncular fossa?
Label
What connects cerebral hemisphere with opposite half cerebellum?
Crus cerebri- form middle peduncle
Label pons?
What sits in basilar sulcus?
Shallow sulcus- basilar artery runs
Label?
What are the 3 cerebellum peduncles?
Superior
Middle
Inferior
Label?
Function superior and inferior colliculi?
Function superior and inferior brachium
Superior col- visual
Inferior col- auditory
Superior brach- visual info from lateral geniculate body to superior colliculi
Inferior brach- auditory info from medial geniculate body to inferior colliculi
MALES- Lateral is superior colliculus
- Medial is inferior colliculus
MALE- medial geniculate auditory
- lateral geniculate eye (vision)
I’MAuditory
I- inferior colliculus
M- medial geniculate body
Default- superior colliculus ald lateral geniculate- visual
Label
What forms visual system?
Superior colliculus and lateral geniculate body
What forms auditory system?
Inferior colliculus and medial geniculate body
1) Oculomotor nerve (CN III)
2) Optic nerve (CN II)
3) Trochlear nerve (CN IV)
4) Trigeminal nerve (CN V)
5) Abducens nerve (CN VI)
6) Vestibulocochlear nerve (CN VIII)
7) Glossopharyngeal nerve (CN IX)
8) Facial nerve (CN VII)
9) Vagus nerve (CN X)
10) Spinal Accessory nerve (CN XI)
11) Hypoglossal nerve (CN XII)
Label
Label
Outline cranial nerves
Modality
Function
Foramen
Cranial nerves function m, s, both?
Function
Some Say Marry Money But My Brother Says Big Boobs Matter More
Outline visual pathway?
1) Optic nerve
2) Optic chiasm
3) Optic tract
4) Lateral geniculate body
5) Internal capsule
5) Visual cortex of occipital lobe
Outline visual pathway- draw
Axons on left LON pick up- left nasal field
Axons on left RON pick up- right temporal
- cross optic chiasm
Meet left geniculate nucleus
Axons right RON pick up- right nasal field
Axons right LON pick up- left temporal
- cross optic chiasm
Axons at nasal retina responsible temporal
Axons at temporal retina responsible nasal
Fibres from nasal portion of the retina (carrying the TEMPORAL visual fields) cross at the optic chiasm
Which fibres cross at chiasm?
Fibres from nasal portion of the retina (carrying the TEMPORAL visual fields) cross at the optic chiasm
Where do fibres carry info from inferior portions retina (superior visual fields) travel?
What loop?
Loop laterally through temporal lobe to visual cortex
Meyers loop
Where do fibres from superior retina (therefore the INFERIOR visual fields) travel?
Loop superiorly through parietal lobe to visual cortex
What fibres travel in meyers loop?
Fibres carry info from inferior portion retina
Superior visual field
Loop laterally through temporal lobe to visual cortex
What does pituitary tumour cause?
Bitemporal hemianopia
Impaired peripheral vision in outer temporal
Press optic chiasm where nerve fibres from both ON cross
Left optic nerve lesion what will occur?
Blindness left eye
Left anopia
Lesion optic chiasm- pit tumour what will occur?
Nerves that capture temporal unable pass
Bitemporal hemianopia
Lesion after optic chiasm on left?
Lose vision left nasal, right temporal
Right homonymous hemiopia
Lesion after optic chiasm on left?
Lose vision left nasal, right temporal
Right homonymous hemiopia
Where are cones and rods concentrated?
Fovea
Damage meyers cause what?
Right superior Quadrantanopia
Loss vision superior quadrant
Left temporal lesion
What would cause damage to meyers?
Left temporal lesion
What would damage to Baums lead to?
What nerve carries axons of cells of retina?
1) Optic nerve
What does optic nerve pass through?
Optic canal
Outline visual field pathway
1) Photoreceptors in retina stimulated by photons of light
2) Light sensitive membrane proteins (rhodopsin) stimulate conversion light energy into electrical signals
3) Photoreceptors synapse with retinal bipolar cells which transmit signals to retinal ganglion cells
4) Retinal ganglion cells converge optic disc and form optic nerve
5) Optic nerve exits eye through cavernous sinus
6) Left and right optic nerves converge at optic chiasm
7) Fibres from nasal aspect of retina decussate to contralateral
8) Fibres from temporal retina remain on sides
9) Optic tracts extend from chiasm to thalamus
10) Synapse at lateral geniculate nucleus
11) Radiate to occipital lobe
12) Optic radiations travel parietal or temporal (Meyers) lobe
13) Optic radiations terminate in calcarine sulcus of occipital lobe
14) Calcarine sulcus responsible retinal image processeing
Function of calcarine sulcus?
Retinal image processing
What fibres decussate?
Fibres from nasal
Briefly outline visual pathway?
Retina
Optic nerve
Optic chiasm
Optic radiations
Visual centre occipital lobe
At optic chiasm what fibres decussate?
Fibres from nasal half retina- correspond temporal visual field
What do optic nerve lesions result in?
Ipsilateral blindness one eye
Lesion optic chiasm causes what? Why what could cause?
Bitemporal hemianopia
At the optic chiasm, fibres from the nasal half of the retina, corresponding to the temporal visual field, decussate.
Pituitary tumour/adenoma
What do lesions optic radiations cause?
Contralateral quadrantanopia
Meyers- pie in sky
Parietal- baums- lower quadrantinopia
What do pre-chiasmal lesions result in?
ipsilateral monocular visual field
What do post=chiasmal lesions result in?
homonymous visual field defects of the contralateral side
What do lesions chiasm result in?
Bitemporal hemianopia
What do lesions chiasm result in?
Bitemporal hemianopia
QUESTIONS
QUESTIONS
State cranial nerve travels through cavernous sinus?
Optic nerve
Where do the majority of the descending fibres of the corticospinal tract decussate
Medulla
